This change moves all of Servo's WPT Python support scripts into one
directory as they were previously scattered throughout the directory
structure. This should allow more code reuse and make it easier to
understand how everything fits together.
The changes:
- `tests/wpt/update` → `python/wpt/importer`
- `etc/ci/upstream-wpt-changes/wptupstreamer` → `python/wpt/exporter`
- `etc/ci/upstream-wpt-changes/test.py` → `python/wpt/test.py`
- `etc/ci/upstream-wpt-changes/tests` → `python/wpt/tests`
- `tests/wpt/servowpt.py` →
- `python/wpt/update.py`
- `python/wpt/run.py`
- `tests/wpt/manifestupdate.py` → `python/wpt/manifestupdate.py`
This change also removes
- The ability to run the `update-wpt` and `test-wpt` commands without
using `mach`. These didn't work very well, because it was difficult
to get all of the wptrunner and mach dependencies installed outside
of the Python virtualenv. It's simpler if they are always run through
`mach`.
- The old WPT change upstreaming script that was no longer used.
After WPT moves to "Manifest path trie RFC", we don't have the `paths`
field in manifest anymore.
But, we still have file hash in the `items` field; the simplest way to
diff between manifests is to compare the raw string value of the `items`
field. When we have different manifests, we must have different items
field in the manifest json.
